PRESS RELEASE

    IAPMO and ASPE Co-publish Capacities of Stacks and Horizontal Drains in Storm Drainage Systems White Paper

    IAPMO and ASPE Co-publish Capacities of Stacks and Horizontal Drains in Storm Drainage Systems White Paper

    Ontario, Calif. — The International Association of Plumbing and Mechanical Officials (IAPMO®) and the American Society of Plumbing Engineers (ASPE) have co-published White Paper 2-2024: Capacities of Stacks and Horizontal Drains in Storm Drainage Systems.

    The sizing for storm drainage systems is dependent upon flow capacity equations used to calculate velocities and flow rates in pipe conduits. One of the variables in the equations is the coefficient of roughness. This white paper explores how the roughness of different types of material will change the computational results that are dependent upon the roughness coefficient of the pipe.

    “Storm drainage systems play a vital role in building resiliency as they convey water off the roof, said IAPMO Vice President of Technical Services and Research Christoph Lohr, PE. “Studying storm piping systems is important to make sure these systems are not undersized, as the weight of water on a roof could exceed design parameters and fail, which could be catastrophic. With changing weather patterns, particularly rainfall rates increasing in many locations, revisiting assumptions and validating the equations of how storm piping systems are sized is vital. We are thankful to our partners at ASPE for collaborating with us on this white paper, which shows the depth of plumbing expertise exhibited by both organizations and their dedication to public safety.”

    The IAPMO/ASPE white paper is available for free download HERE

    ABOUT IAPMO
    Founded in 1926, the International Association of Plumbing and Mechanical Officials is a global leader in providing uniform codes for the plumbing and mechanical industry. IAPMO protects health and safety, supports sustainability and emerging technology, and delivers code education.

    ABOUT ASPE
    The American Society of Plumbing Engineers (ASPE) is the international organization for professionals skilled in the design, specification and inspection of plumbing systems. ASPE is dedicated to the advancement of the science of plumbing engineering, to the professional growth and advancement of its members and the health, welfare and safety of the public.

    For questions, please contact Christoph Lohr at (909) 731-0219 or christoph.lohr@iapmo.org; or Hugo Aguilar at (909) 472-4111 or hugo.aguilar@iapmo.org.

    Pacific Institute Report Recommends IAPMO’s Water Demand Calculator as a Key Strategy for National Water Efficiency

    04 November 2025

    Ontario, California — IAPMO®, a global team of experts engaging industry and government for a safer built environment, is proud to announce that its Water Demand Calculator® has been featured as a key recommendation in the Pacific Institute’s new landmark report, “Untapped Potential: An Assessment of Municipal and Industrial Water Efficiency Potential in the United States.”

    Blueprint for Progress: IAPMO at the ANSI Innovation Summit Demonstrates How Codes and Standards Advance U.S. Competitiveness and Public Health

    21 October 2025

    IAPMO® is proud to be a diamond sponsor and administrating organization at the 2025 ANSI Innovation Summit this week. Formerly World Standards Week, the ANSI Innovation Summit is an annual event that convenes the Institute's members and private- and public-sector stakeholders from across the standards and conformity assessment communities to come together, learn from each other, and showcase their important work. 

    IAPMO Celebrates 10 Years of WorldSkills Global Industry Partnership

    16 October 2025

    IAPMO®, a global team of experts engaging industry and government for a safer built environment, and its charitable foundation, the International Water, Sanitation and Hygiene Foundation (IWSH®), are proud to celebrate 10 years as a WorldSkills Global Industry Partner. IAPMO and IWSH celebrated the milestone this week at the annual General Assembly of WorldSkills International Members in Dubrovnik, Croatia.

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